Method for treating blade of hair clipper by ion irradiation

ABSTRACT

The present invention relates to a method for treating a surface of blade of a hair clipper, in which a nitrogen ion beam is irradiated to an edge of the blade at a predetermined angle with respect to the normal of the blade surface, to prevent the blade from becoming blunt, to remove undesirable adsorbents from the blade surface and to reduce surface roughness of the blade using sputtering effect due to the collision of nitrogen ions to the blade, and to form hard Cr—N and Fe—N particulates on an edge as well as on a surface of the blade. The method is advantageous in that surface-frictional coefficient of the blade is reduced, thereby improving durability and life of the blade.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a method for treating a surface of blade of a hair clipper and, in particular, to a method for treating a surface of blade of a hair clipper, in which a nitrogen ion beam is irradiated to an edge of the blade at a predetermined angle with respect to the normal of the blade surface, to prevent the blade from becoming blunt, to remove undesirable adsorbents from the blade surface and to reduce surface roughness of the blade using sputtering effect due to the collision of nitrogen ions to the blade, and to form hard Cr—N and Fe—N particulates on an edge as well as on a surface of the blade.

[0003] 2. Description of the Prior Art

[0004] As well known to those skilled in the art, quality and life of a blade of a hair clipper consisting of stainless steel depend on a method of treating the blade. Additionally, in order to lengthen the blade's useful life, the blade must consist of materials with high hardness, and need to be kept with care. Otherwise, the blade becomes easily blunt, so when users cut customers' hair using the hair clipper with the blunt blade, the customers feel painful because hairs of the customers are apt to be pulled up rather than be trimmed.

[0005] To use the blade for a long period, it is preferred that the blade is brushed off, sterilized using an antiseptic solution, dried, kept in a sterile cabinet, and frequently sharpened.

[0006] Particularly, it is important to properly care for a cutting edge of the blade directly coming into contact with the hairs, and the life of the cutting edge of the blade depends on surface hardness of the blade. However, the blade consisting of a material with high hardness is disadvantageous in that it is difficult to treat a surface of the blade and its price is undesirably high because the blade made of harder materials is higher-priced, even though the blade with higher hardness has advantages in that its life is prolonged.

[0007] As an alternative, it may be considered to improve surface properties of the blade so as to prolong the life of the blade. For example, physical and chemical coating processes on the blade or processes of directly treating the surface of the blade may be used to improve surface properties of the blade. These two processes have advantages and disadvantages with each other, and may be simultaneously applied to obtain synergetic effects in improving the surface properties of the blade. Examples of the process of directly treating the surface of the blade include a mechanical process and a chemical process. However, in recent, the blade is treated using an electron beam, a laser beam, or a plasma/ion beam so as to effectively improve surface properties of the blade, and demand for the use of the above beams is gradually growing.

[0008] In the physical and chemical coating processes, the thin film consisting of hard substances is coated on the blade materials with lower hardness to enhance surface hardness of the blade and to reduce materials and treatment costs of the blade. However, this process is often disadvantageous in that when an adhesive force between the thin film and the blade (especially at the blade edge rather than the blade surface) is weak, the thin film is easily peeled from the blade, thereby causing the blade to be spoiled. This is a general problem in the coated parts even though recent efforts have produced many solutions against the peeling problem.

[0009] In order to lead the present invention, an intensive and thorough research into improvement of surface properties of the blade using various ion beams so as to prolong the life of the blade was carried out by the present inventors to solve the problems encountered in the prior arts, resulting in the finding that a nitrogen ion beam can be irradiated onto a cutting edge of the blade made of stainless steel at a predetermined angle to implant the nitrogen ions into the blade with preventing the blade from becoming blunt. In this process, the tilted angle irradiation with respect to the blade surface removes undesired fillings on the blade surface, which may be induced from polishing pastes, and reduces surface roughness of the blade using a sputtering effect due to the collision of ions to the blade surface, and forms very hard Cr—N and Fe—N particulates on a surface of the blade without additional heat treatments, thus frictional coefficient of the blade is reduced to improve durability and life of the blade, thereby accomplishing the present invention.

SUMMARY OF THE INVENTION

[0010] Therefore, the present invention has been made keeping in mind the above disadvantages occurring in the prior arts; and an object of the present invention is to provide a method for prolonging life of a blade of a hair clipper.

[0011] It is another object of the present invention to provide a method for treating a surface of blade of a hair clipper by irradiating an ion beam to the blade so as to prolong life of the blade.

[0012] It is still another object of the present invention to provide a blade of a hair clipper, which is improved in terms of surface hardness and abrasion resistance by irradiating an ion beam to the blade.

[0013] It is yet another object of the present invention to provide a method for improving surface properties of a blade of a hair clipper, which prevents the blade from becoming blunt, removes filings on a surface of the blade and reduces surface roughness of the blade using sputtering effect due to the collision of ions to the blade.

[0014] Based on the present invention, the above object can be accomplished by providing a method of treating a blade of hair clipper, comprising irradiating a nitrogen ion beam to the blade at a predetermined angle to form Cr—N or Fe—N particulates on the blade.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

[0016]FIG. 1 is a graph showing a depth of nitrogen ion penetration into the blade as a function of a sputtering time in the case of irradiating nitrogen ions with energy of 70 keV in an amount of 5×10¹⁶ ions/cm² at angles of 30° and 45° to a blade consisting of SUS440A;

[0017]FIGS. 2a and 2 b illustrate X-ray photoelectron spectra showing chemical states of nitrogen atoms irradiated to the blade consisting of SUS440A of FIG. 1;

[0018]FIG. 3a is a graph showing the results of an abrasion test using a blade consisting of SUS440A without the ion-irradiation, and a steel ball with a weight of 500 gf;

[0019]FIG. 3b is a graph showing the results of an abrasion test using a blade consisting of SUS440A and irradiated by nitrogen ions with energy of 70 keV in an amount of 5×10¹⁶ ions/cm² at an angle of 30°, and a steel ball with a weight of 500 gf;

[0020]FIG. 4a is a graph showing the results of an abrasion test using a blade consisting of SUS440A without the ion-irradiation, and an aluminum ball with a weight of 500 gf; and

[0021]FIG. 4b is a graph showing the results of an abrasion test using a blade consisting of SUS440A and irradiated by nitrogen ions with energy of 70 keV in an amount of 5×10¹⁶ ions/cm² at an angle of 30°, and an aluminum ball with a weight of 500 gf.

DETAILED DESCRIPTION OF THE INVENTION

[0022] There will be given a detailed description of the method of treating a blade of a hair clipper using the ion-irradiation, below.

[0023] It should be understood that the term “blade” as used herein is intended to include all kinds of blades for the hair clipper, consisting of stainless steel widely used as a material of the blade. Stainless steel useful in the present invention includes primarily iron (Fe), and chromium (Cr) of 12% or higher, and in the some cases, further includes carbon (C), nickel (Ni), silicon (Si), manganese (Mn), and molybdenum (Mo) in a small amount. Having excellent abrasion resistance, heat resistance, and surface properties, stainless steel may be classified according to chemical composition and metallic structure, for example, it may be classified into SUS440A, SUS440B, SUS431, SUS420, and SUS304. As described above, the blade of the hair clipper useful in the present invention consists of stainless steel. At this time, a kind of stainless steel is not limited.

[0024] Additionally, the term “ion-irradiation” as used herein means the collision of ionized atoms with high energy to a surface of the subject body to allow the ionized atoms to penetrate into the subject body. At this time, the penetration of the ionized atoms into the subject body is accompanied with a sputtering effect which is defined as the separation of atoms or molecules from the surface of the subject body. Additionally, the penetration of the ionized atoms into the subject body depends on a material constituting the subject body, an irradiation angle of the ionized atoms to the subject body, and an amount of the ionized atoms, and is conducted under an optimized condition in the present invention.

[0025] The ionized atoms, that is, ions, may be selected from the group consisting of gases traditionally used in the ion-irradiation, for example, nitrogen (N), carbon (C), argon (Ar), helium (He), xenon (Xe), hydrogen (H), heavy hydrogen (D), and mixtures thereof. In the present invention, nitrogen gas is useful because it is important to form nitrides on the blade owing to physical properties of a material constituting the blade.

[0026] In detail, a nitrogen ion beam with energy of 50 to 300 keV is irradiated to the blade at an angle of 30° to 45° so as to treat the blade of the hair clipper.

[0027] At this time, the energy depends on surface properties of the blade. Higher energy intensity or more ions brings about greater improvements to hardness of the blade and easier removal of oxidants and filings on the surface of the blade. However, if the energy is excessively high or the amount of ions is excessively large, side effects such as damage to the blade may occur and treatment cost of the blade may be undesirably increased, so the energy or the ion-irradiation amount should be controlled in such a way that the blade is sufficiently competitive in terms of physical properties and treatment cost.

[0028] In other words, nitrides with high hardness are formed on the surfaces of the blade by irradiating the ions with the energy of 50 to 300 keV to the blade even though the blade is not separately heat-treated, thereby filings are removed from the surfaces of the blade, surface roughness of the blade is reduced, and durability of the blade is improved. At this time, the amount of ions irradiated to the blade is preferably 5×10¹⁶ to 5×10¹⁷ ions/cm².

[0029] For example, when the ion-irradiation amount is less than 5×10¹⁶ ions/cm², the nitrides are insufficiently formed on the blade, so it is difficult to secure desired physical properties of blade. On the other hand, when the amount is more than 5×10¹⁷ ions/cm², side effects including damage to the blade may occur.

[0030] Particularly, in the present invention, surface durability of the blade depends on a kind of ions and an irradiation angle of the ions to the blade.

[0031] If the ions are irradiated to the blade at a right angle, the blade will be readily damaged, so they are preferably irradiated to the blade at a predetermined slanted angle. The irradiation of the ions to the blade spontaneously brings about the sputtering effect at the surface of the blade, so removing filings from the surface of the blade and reducing surface roughness of the blade.

[0032] It is preferable that the ion-irradiation angle to the blade is a half of an angle between both sides of a cutting edge of the blade. For example, when the angle between both sides of the cutting edge is 60°, the ions are irradiated to the blade at an angle of 30°. However, smaller ion-irradiation angles brings about shallower penetration of nitrogen ions into the blade, so the energy of the ions must be increased in this case.

[0033] According to a first embodiment of the present invention, the nitrogen ions are irradiated to the blade consisting of stainless steel, SUS404A to treat the surfaces of the blade. At this time, most of the nitrogen ions are converted into the nitrides, that is to say, Fe—N and Cr—N are formed on the surface of the blade.

[0034] According to a second embodiment of the present invention, the blade, consisting of SUS404A, irradiated by the nitrogen ions is compared with the blade without being treated by the nitrogen ions in views of mechanical properties and abrasion resistance. Through the comparison, it can be seen that the treated blade has three times higher abrasion resistance than the untreated blade. As for surface roughness, the treated blade is two times lower than the untreated blade. Therefore, the treated blade has a smooth surface in comparison with the untreated blade.

[0035] According to a third embodiment of the present invention, the nitrogen ions are irradiated to blades consisting of SUS404A at angles of 30° and 45°. At this time, nitrides are formed on both blades, but the nitrogen ions are more deeply penetrated into the blade in the case of irradiating the ions to the blade at an angle of 45° than in the case of irradiating the ions to the blade at an angle of 30°.

[0036] Meanwhile, a traditional ion irradiation device may be used to irradiate the ions to the blade of the hair clipper, but components constituting it are not limited.

[0037] In the present invention, an ion irradiation device disclosed in Korean Pat. No. 143,433 having been made by the applicant of the present invention is used to irradiate the ions to the blade while a kind of ions, the energy of the ions, current density of the ions, and an amount of ions are desirably controlled.

[0038] As described above, the ions are irradiated to the blade of the hair clipper to form nitrides on the blade, thus the filings are removed from the surface of the blade, and surface roughness of the blade is reduced, thereby securing excellent surface properties of the blade to prolong life of the blade. Particularly, the blade is mechanically ground to be sharpened and irradiated by ions to reform nitrides thereon after the blade is partially worn, thereby securing economic efficiency.

[0039] A better understanding of the present invention may be obtained in light of the following examples which are set forth to illustrate, but are not to be construed to limit the present invention.

Example 1

[0040] A blade of a hair clipper made of stainless steel consisting of SUS440A (C: 0.6 to 0.75, Mn: 1.00, Si: 1.00, Cr: 16 to 18.00, P: 0.04, S: 0.03, and Mo: 0.75) was ground to have a surface roughness of about 0.04 μm. Then, nitrogen ions with energy of 70 keV were irradiated to the blade in an amount of 5×10¹⁶ ions/cm² at an angle of 30 to 45° using an ion irradiating device to treat surfaces of the blade. TABLE 1 Energy ¹Condition ²Ion (keV) ³Ion amount ⁴Roughness ⁵Angle 1 Nitrogen 70 5 × 10¹⁶ 0.04 30 2 Nitrogen 70 5 × 10¹⁶ 0.04 45

[0041] A. Surface Chemical Analysis of the Blade

[0042] To evaluate surface properties of the blade irradiated by the nitrogen ions, analyses of the blade by an Auger electron spectrum analysis and an X-ray photoelectron spectrum (XPS) analysis were conducted as follows.

[0043] 1) Auger electron spectrum analysis

[0044] After the nitrogen ions were injected into the treated blade of the hair clipper, a nitrogen atom distribution in the blade was analyzed using a depth profiling technology while cutting flakes from the blade to a predetermined depth. The results are described in Table 1.

[0045]FIG. 1 is a graph showing a depth of the nitrogen ions penetrated into the blade as a function of a sputtering time in the case of irradiating nitrogen ions with energy of 70 keV in an amount of 5×10¹⁶ ions/cm² at angles of 30° and 45° to a blade consisting of SUS440A. From the FIG. 1, it can be confirmed that the nitrogen ions are penetrated into the blade to a considerable depth and they reach to a deeper position in the case of irradiating the nitrogen ions to the blade at an angle of 45° than in the case of irradiating the nitrogen ions to the blade at an angle of 30°. Accordingly, it is seen that the smaller the ion-irradiation angle to the blade is, the shallower the penetration depth of the nitrogen ions is.

[0046] 2) X-ray photoelectron spectrum analysis

[0047] A treated surface of the blade of the hair clipper was analyzed using an X-ray analyzer, and the results are illustrated in FIGS. 2a and 2 b.

[0048]FIGS. 2a and 2 b illustrate X-ray photoelectron spectra showing chemical states of nitrogen atoms irradiated to the blade consisting of SUS440A of FIG. 1. From the FIGS. 2a and 2 b, it can be confirmed that most of the nitrogen ions irradiated to the blade are converted into nitrides such as Fe—N and Cr—N in FIG. 2b unlike FIG. 2a.

[0049] B. Surface Properties of the Blade

[0050] To evaluate surface properties of the blade irradiated by the ions, a friction and abrasion test using the blade and a ball was conducted using a Pin-On-Disk type of friction and abrasion tester, in which balls are used instead of pins, so as to test the blade under test conditions similar to practical environment. In this regard, load of 500 gf was applied to the blade using a stainless steel and an alumina ball, which is heavier than a load applied to the blade in practical use, in order to quickly complete the friction and abrasion test. The results are illustrated in FIGS. 3a to 4 b. The reason why balls consisting of two different materials are used is that a lower side of the blade consists of stainless steel but an upper side of the blade consists of stainless steel or ceramics.

[0051]FIGS. 3a and 3 b are graphs respectively showing a frictional coefficient as a function of an abrasion locus so as to evaluate abrasion resistance of the blade when the stainless steel ball with a weight of 500 gf is applied to the blade before the ion-irradiation (FIG. 3a) and after the ion-irradiation (FIG. 3b).

[0052] From the FIGS. 3a and 3 b, it can be seen that the blade with the treated surface has the much wider abrasion locus, within a region that the frictional coefficient is rapidly increased, than the untreated blade, thus the abrasion resistance of the treated blade is 1.5 times higher than the untreated blade.

[0053]FIGS. 4a and 4 b are graphs respectively showing a frictional coefficient as a function of an abrasion locus so as to evaluate abrasion resistance of the blade when the alumina ball with a weight of 500 gf is applied to the blade before the ion-irradiation (FIG. 3a) and after the ion-irradiation (FIG. 3b).

[0054] From the FIGS. 4a and 4 b, it can be seen that the blade with the treated surface has the much wider abrasion locus, within a region that the frictional coefficient is rapidly increased, than the untreated blade, thus the abrasion resistance of the treated blade is 3 times higher than the untreated blade.

[0055] C. Surface Roughness

[0056] Surface roughnesses of the untreated blade and the treated blade were evaluated using Sutftest SJ-301 manufactured by Mitutoyo Co..

[0057] When the blade consisting of stainless steel irradiated by ions was compared with the untreated blade in view of surface roughness, surface roughness of the treated blade was about 0.02 μm but that of the untreated blade is 0.04 μm. Accordingly, it can be seen that surface roughness of the blade treated by the ions is relatively reduced in comparison with that of the untreated blade.

[0058] D. Conclusion

[0059] Nitrogen ions with energy of 70 keV were collided to mechanically treated blade made of stainless steel consisting of SS440A (C: 0.6 to 0.75, Mn: 1.00, Si: 1.00, Cr: 16 to 18.00, P: 0.04, S: 0.03, and Mo: 0.75) in an amount of 5×10¹⁶ ions/cm² at an angle of 30 to 45°. In this regard, removal of fillings and reduction of surface roughness by sputtering effect, and formation of nitrides by the ion-irradiation were observed.

[0060] The surface roughness was 0.04 μm before the ion-irradiation and 0.02 μm after the ion-irradiation. Further, analysis of the blade by XPS confirmed that the fillings generated during mechanical grinding of the blade using a diamond wheel were removed from the surface of the blade due to sputtering effect, and it was seen that CrN and FeN are formed on a subsurface of the blade through analysis of combination energy of Nls electrons.

[0061] As described above, the present invention provides a method of treating a blade of a hair clipper, in which a nitrogen ion beam is irradiated to an edge of the blade at a predetermined angle to prevent the blade from becoming blunt, remove fillings from the blade and reduce surface roughness of the blade using sputtering effect due to the collision of nitrogen ions to the blade, and form light Cr—N and Fe—N particulates on a surface of the blade. Accordingly, surface-frictional coefficient of the blade is reduced, thereby improving durability and life of the blade.

[0062] Particularly, in the present invention, the blade is ground and irradiated by ions to reform nitrides thereon, that is to say, regenerate the blade, after the blade is partially worn, thereby securing economic efficiency. Furthermore, the blade of the hair clipper according to the present invention can endure compression pressure of 500 gf or lower, thus improving the life of the blade unless the blade is subjected to severe abrasion.

[0063] The present invention has been described in an illustrative manner, and it is to be understood that the terminology used is intended to be in the nature of description rather than of limitation. Many modifications and variations of the present invention are possible in light of the above teachings. Therefore, it is to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described. 

What is claimed is:
 1. A method for treating a surface of blade of a hair clipper, comprising: irradiating ions at an angle of 30 to 60° to the blade made of stainless steel to form nitrides on the blade, wherein the angle depends on a shape of the blade.
 2. The method according to claim 1, wherein the stainless steel is selected from the group consisting of SUS440A, SUS440B, SUS431, SUS420, and SUS304, which traditionally used as a material of a blade for hair clipper.
 3. The method according to claim 1, wherein the ions include only nitrogen ions, or nitrogen ions and other ions containing carbon.
 4. The method according to any one of claims 1 to 3, wherein the energy range of ions is 50 to 300 keV.
 5. The method as set forth in any one of claims 1 to 3, wherein the dosage of ions is 5×10¹⁶ to 5×10¹⁷ ions/cm². 